What is the change in internal energy if 20 j of heat is released from a system and the system does 50 j of work on the surroundings?
a.-80 j
b.-20 j
c.80 j
d.20 j

C. 80 J

Explanation:

dU = dq + w

dU = -20 J + (-60 J) = -80 J

the minimum amperage that the current in this wire would have to have so that its weight is completely supported by the magnetic force due to earth's field, assuming that no other forces except gravity act on it

myth. it was once thought that animals, including cats and dogs, could only see in black and white. however, scientists have proven this to be a myth. in all animals, including humans, the perception of colour is determined by the presence of cells in the eye called cone photoreceptors.